/Engine/Source/Runtime/Engine/Classes/Materials/MaterialInstanceConstant.h
Set the value parameters. These functions may be called only in the Editor! WARNING: You MUST call PostEditChange afterwards to propagate changes to other materials in the chain!
void SetVectorParameterValueEditorOnly ( const [FMaterialParameterInfo](API\Runtime\Engine\FMaterialParameterInfo) & ParameterInfo, [FLinearColor](API\Runtime\Core\Math\FLinearColor) Value )